We studied the developmental trajectories of satisfaction with work–family reconciliation (WFS) and their associations with family—related factors and quality of life measures among municipal employees. The study was based on the Helsinki Health Study of municipal employees of the City of Helsinki in 2001–02 and its follow-up surveys in 2007, 2012, and 2017. Employees aged 40–50 at baseline and working at all timepoints were analysed (n = 1681, 84% women). Growth Mixture Models were applied to identify trajectories of WFS (dissatisfied vs. satisfied). Associations of family-related and quality-of-life factors (physical functioning and emotional well-being) with the WFS trajectories were studied using log-binomial regression models, adjusting for sociodemographic and lifestyle variables. Two WFS trajectories, low (women 45%; men 53%) and high were identified. In a fully adjusted model among women, having ≥1 children aged 0–6 years was associated with increased odds of belonging to the low WFS trajectory (OR 1.52, 95% CI 1.19–1.95). Among men, having ≥1 children aged 7–18 was associated with decreased odds (0.39, 0.19–0.80). High emotional well-being was inversely associated with the low WFS trajectory among both genders (women 0.32, 0.23–0.45; men 0.20, 0.09-0.46). High physical functioning (0.59, 0.42–0.83) was inversely associated with the low WFS trajectory among women only. Less than half of the women and more than half of the men participants belonged to a low WFS trajectory, which associated with the age of children in the family and quality-of-life measures.